Harnessing Bioenergy from Everyday Rubbish

Converting everyday rubbish into usable energy once seemed like science fiction, but bioenergy has made it reality. This sustainable solution transforms waste into valuable fuel sources while also benefiting the environment.

Bioenergy provides a profitable way to upcycle discarded items into clean power instead of letting them pile up in landfills. What was once treated as garbage now becomes a source of renewable energy for society’s needs. With bioenergy, there is potential to turn waste into an environmental and economic asset.

bioenergy from municipal waste

Definition of Bioenergy

You might be wondering what exactly is bioenergy? In simple terms, bioenergy is energy derived from organic materials. These materials can range from agricultural residues, forest waste, food scraps or even animal manure. The process of converting these ‘biomass’ resources into bioenergy can take several forms, like burning for heat and power, fermenting for biofuels or subjecting them to anaerobic digestion to generate biogas.

Various Sources of Bioenergy

Nature offers an abundance of sources for generating bioenergy. You have wood pellets and chips from forests, manure from farming activities, crop residues left after harvests and even energy crops grown explicitly for this purpose like switchgrass or miscanthus. The spectrum doesn’t end here though; household waste also qualifies as a potential contributor to this list which you will explore more next.

Understanding Everyday Rubbish

If you were thinking that household rubbish is just useless trash, think again! Household waste consists of food scraps, glass bottles, plastic containers, paper products – stuff that you discard every day. This seemingly insignificant rubbish when recycled correctly can generate appreciable amounts of bioenergy contributing towards sustainable energy practices for society.

Contribution of Rubbish Removals

The company Same Day Rubbish Removals plays a significant part in Melbourne’s waste management ecosystem by providing quick and efficient removal services. They responsibly handle all types of waste – from household junk to electronic waste and green waste which can boost the raw material sources for bioenergy. You can see the services on offer here https://www.samedayrubbishremovalmelbourne.com.au/.

Beyond mere rubbish collection and disposal, they also advocate for proper recycling which aligns perfectly with the ideal principles of bioenergy generation and closing the loop on waste management for a sustainable future.

Importance of Bioenergy

Bioenergy today holds tremendous importance in the roadmap towards carbon neutrality. It serves as a renewable alternative to fossil fuels thus reducing our carbon footprint. Not only for large industries, but it can also be adopted at the community level through bioenergy plants helping cities reduce their reliance on non-renewable energy sources. The end products such as electricity, heat or biofuels have wide applications across sectors.

 

Role of Everyday Rubbish

Everyday rubbish plays a crucial role in this bioenergy narrative. Home waste when segregated correctly can segregate organic wastes fit for conversion into bioenergy. Post-consumer packaging materials, when recycled, could divert significant volumes of waste from landfills and transform them into value-added bioenergy resources. Our household waste has the potential to shift the energy paradigm!

Detailed Process of Conversion

The conversion of biomass into bioenergy isn’t just a one-step process. It involves several stages: collection, separation and treatment followed by chemical reactions that help extract energy. Techniques such as anaerobic digestion turn organic wastes into biogas or advanced thermal technologies like gasification that convert solid waste into synthetic fuels.

Everyday Rubbish to Bioenergy: How?

If you are curious about how everyday rubbish transforms into bioenergy, carry on reading! Organic kitchen wastes or garden clippings undergo anaerobic digestion in specially designed digesters to produce methane-rich gas which is subsequently burnt to generate heat and electricity. Non-organic materials like plastics get subjected to advanced thermal methods to produce an oil-like substance that can substitute crude oil in refineries.

Benefits of Bioenergy Production

Bioenergy production brings multiple perks. Obviously, the generation of renewable energy is its biggest appeal, allowing us to cut back on fossil fuel usage. However, it’s also a great solution for managing waste more effectively and reducing the volume going to landfills daily. Additionally, it promotes recycling and could stimulate new employment and business opportunities in the waste management sector.

Anaerobic Digestion of Food Wastes

Challenges in Bioenergy Harnessing

Despite its myriad of benefits and potentials, bioenergy faces certain challenges that need to be tackled effectively. Issues such as high initial capital costs for setting up bioenergy plants and the lack of advanced technology for efficient transformation remain roadblocks. Apart from these, there is also a considerable lack of energy subsidies and regulatory policies favoring bioenergy.

Apart from this, the fluctuating biomass feedstock prices could affect the economic viability of bioenergy projects. Also, the public’s perception towards waste-to-energy conversion and their willingness to segregate their waste can also pose uncertainties in success rates.

Role of Technology in Bioenergy

Technology plays an irreplaceable role in streamlining and accelerating the conversion of everyday rubbish into bioenergy. Advanced processing technologies like anaerobic digestion, gasification, pyrolysis and fermentation not only make bioenergy production possible but have been instrumental in increasing its efficiency over time.

This evolution has been further revolutionized by innovations like next-generation sequencing techniques that promise improvements in the variety and capacity of bio-energy fuels achievable from waste.

The Concept of Waste Hierarchy

The concept of the waste hierarchy revolves around three key principles: reduce, reuse, and recycle. This system places a high emphasis on reducing waste generation to the maximum extent possible, reusing materials as long as their useful life permits and recycling what’s left to extract maximum value.

This strategy is fundamental to converting rubbish into bioenergy. The better people adhere to these principles, the more efficiently people can convert everyday waste into bioenergy fueling a closed-loop circular economy.

International Approaches to Bioenergy

The adoption of bioenergy strategies varies worldwide. In Europe, especially in countries like Germany and Sweden, aggressive renewable energy policies have promoted significant advances in bioenergy generation from waste. Conversely, in developing regions like Africa and South America, biomass-based heating and power applications are mainly used due to infrastructure constraints.

Every nation has different potential and challenges in embracing bioenergy. What’s crucial is adapting technologies to the specifics of each nation to fully harness the potential of waste-based bioenergy.

Different Bioenergy Technologies

There is a broad array of technologies that enable the transformation of rubbish to bioenergy. Anaerobic digestion and fermentation techniques predominantly deal with organic materials like food waste and crop residues. Pyrolysis and gasification are more suited for non-organic waste, converting complex matter into simpler forms that can be burned as fuels or further processed into biofuels or chemicals.

Such a spectrum of technologies can address varying types of wastes and produce diverse outputs making waste management versatile and flexible.

Policies on Bioenergy and Waste Management

Effective policies can stimulate bioenergy production from everyday rubbish removal. Strong waste management regulations coupled with initiatives that incentivize bioenergy projects could expedite the adoption of this technology in not only industries but also smaller communities.

Acknowledging the environmental benefits of waste-based bioenergy through a carbon credit system can create an enabling environment for this sector to thrive.

The Summary

Synthesizing bioenergy from rubbish is a poignant example of sustainability in action. As people strive towards a cleaner planet, this alternate strategy could play a significant role. It’s about viewing our wastes not as a problem, but as an answer. To paraphrase Da Vinci, you know you have learned enough when you have grasped the principle of turning everything harmful into something beneficial. That is undoubtedly what converting solid waste into bioenergy achieves.

How Food Waste and Recycling Could Generate Bioenergy

Food waste is a major issue globally, with an estimated 1.3 billion tons of food wasted each year. This not only contributes to greenhouse gas emissions but also wastes valuable resources such as water and energy. However, there is a solution that not only tackles food waste but also generates bioenergy: food recycling.

bioenergy from food waste recycling

What is Food Recycling?

Food recycling is the process of taking food waste and turning it into a useful resource. This can be done through a variety of methods, including composting, anaerobic digestion, and fermentation. The result is a valuable product that can be used as a fertilizer or as a source of energy.

Generating Bioenergy from Food Waste

One of the most promising applications of food waste recycling is the generation of bioenergy. Bioenergy is a form of renewable energy that is derived from organic matter, such as food waste. By using food waste to generate bioenergy, we can reduce our dependence on fossil fuels and decrease our carbon footprint.

1. Anaerobic Digestion

Anaerobic digestion is one of the most common methods of generating bioenergy from food waste. This process involves breaking down organic matter in the absence of oxygen, producing biogas as a by-product. Biogas is a mixture of methane and carbon dioxide that can be burned to generate electricity or heat.

The process of anaerobic digestion starts with the collection of food waste. This can be done at a household level, with individuals separating their food waste from other types of waste. Alternatively, food waste can be collected from commercial and industrial sources, such as restaurants and food processing plants.

Once collected, the food waste is transported to an anaerobic digestion facility, where it is mixed with water and placed in a sealed tank called a digester. Inside the digester, bacteria break down the organic matter in the absence of oxygen, producing biogas as a by-product. The biogas is then collected and used to generate electricity or heat.

Advantages of Anaerobic Digestion

One of the advantages of anaerobic digestion is that it can be done on a small scale, making it a viable option for households and small businesses. In fact, many households in rural areas use small-scale anaerobic digesters to generate their own electricity and heat.

biogas-enrichment

Another advantage of anaerobic digestion is that it produces a valuable fertilizer as a by-product. The residue left over from the process, known as digestate, is a nutrient-rich material that can be used as a fertilizer for crops.

2. Fermentation

Fermentation is another method of generating bioenergy from food waste. This process involves breaking down organic matter using microorganisms, such as yeast or bacteria. The result is a product such as ethanol or biobutanol, which can be used as a fuel for vehicles or as a source of energy.

The process of fermentation starts with the collection of food waste, which is then mixed with water and enzymes to break down the organic matter. Microorganisms are then added to the mixture, which ferment the organic matter and produce ethanol or biobutanol as a by-product.

Advantages of Fermentation 

Like anaerobic digestion, fermentation can be done on a small scale, making it a viable option for households and small businesses. However, it is not as common as anaerobic digestion, as it requires more specialized equipment and expertise.

Role of Food Waste Disposers in Food Waste Management

Food waste is a global issue that begins at home and as such, it is an ideal contender for testing out new approaches to behaviour change. The behavioural drivers that lead to food being wasted are complex and often inter-related, but predominantly centre around purchasing habits, and the way in which we store, cook, eat and celebrate food.

food-waste-management

Consumer Behavior – A Top Priority

Consumer behaviour is a huge priority area in particular for industrialised nations – it is estimated that some western societies might be throwing away up to a third of all food purchased. The rise of cheap food and convenience culture in recent years has compounded this problem, with few incentives or disincentives in place at producer, retail or consumer level to address this.

While it is likely that a number of structural levers – such as price, regulation, enabling measures and public benefits – will need to be pulled together in a coherent way to drive progress on this agenda, at a deeper level there is a pressing argument to explore the psycho-social perspectives of behaviour change.

Individual or collective behaviours often exist within a broader cultural context of values and attitudes that are hard to measure and influence. Simple one-off actions such as freezing leftovers or buying less during a weekly food shop do not necessarily translate into daily behaviour patterns. For such motivations to have staying power, they must become instinctive acts, aligned with an immediate sense of purpose. Click here to see what steps you can take to tackle this issue. The need to consider more broadly our behaviours and how they are implicated in such issues must not stop at individual consumers, but extend to governments, businesses and NGOs if effective strategies are to be drawn up.

Emergence of Food Waste Disposers

Food waste disposer (FWDs), devices invented and adopted as a tool of food waste management may now represent a unique new front in the fight against climate change. These devices, commonplace in North America, Australia and New Zealand work by shredding household or commercial food waste into small pieces that pass through a municipal sewer system without difficulty.

The shredded food particles are then conveyed by existing wastewater infrastructure to wastewater treatment plants where they can contribute to the generation of biogas via anaerobic digestion. This displaces the need for generation of the same amount of biogas using traditional fossil fuels, thereby averting a net addition of greenhouse gases (GHG) to the atmosphere.

Food waste is an ideal contender for testing new approaches to behaviour change.

The use of anaerobic digesters is more common in the treatment of sewage sludge, as implemented in the U.K., but not as much in the treatment of food waste. In addition to this, food waste can also replace methanol (produced from fossil fuels) and citric acid used in advanced wastewater treatment processes which are generally carbon limited.

Despite an ample number of studies pointing to the evidence of positive impacts of food waste disposer, concerns regarding its use still exist, notably in Europe. Scotland for example has passed legislation that bans use of FWDs, stating instead that customers must segregate their waste and make it available curbside for pickup. This makes it especially difficult for the hospitality industry, to which the use of disposer is well suited.

The U.S. however has seen larger scale adoption of the technology due to the big sales push it received in the 1950s and 60s. In addition to being just kitchen convenience appliances, FWDs are yet to be widely accepted as a tool for positive environmental impact.

Note: Note: This excerpt is being published with the permission of our collaborative partner Be Waste Wise.

The Role of Bioengineering in Sustainable Food Supply Chain

Every year, the production of food around the world accounts for almost a third of all global emissions of greenhouse gases. Deforestation, grazing livestock, and the use of fertilizers all contribute to climate change. Finding ways to minimize the damage that food production causes is becoming a priority in the fight against global warming. In addition, the United Nations’ Food and Agriculture Organization has estimated that every year, the world produces enough food waste to feed 2 billion people.

To address these problems, the field of bioengineering has found ways to recycle scrap food, reduce the amount thrown away, and find alternative ways to produce sufficient food to feed the world more sustainably and with less waste.

sustainability-food-supply-chain

Engineering Sustainable Food

A degree in bioengineering, or a masters in biomedical engineering online, involves the study of a range of scientific fields from computational biology and physiological systems to mechanical engineering and material sciences. This multidisciplinary approach lends itself well to improving the sustainability of food production. For many years, the genetic engineering of plants has created the potential of increasing production in a sustainable and environmentally-friendly way, and more recently, progress has been made in creating synthetic meat.

Now, without the use of genetic engineering, biomedical engineers have created the first bioprinted steak from cattle cells. The qualities of real meat are replicated by allowing living cells to grow and interact in the same way as they would in nature. The result is the creation of an authentic-tasting steak produced without the extensive environmental damage caused by farming livestock.

Converting Food Into Fuel

Every year in the US alone, 80 billion pounds of food is thrown away without being eaten. An increasing number of scientific projects are working on harnessing the valuable energy from food waste and converting it into renewable fuel. This can then be used to power a range of vehicles from privately owned cars to planes and trains.

In communities where food waste is collected along with other recyclable materials, anaerobic digestion can also be used to convert the high fat content of food waste into green electricity, which is put back into the grid to power households.

food-waste-behavior

Reducing Food Waste

Some food scraps are unavoidable, but now bioengineering is being applied to reduce some of the waste from over consumerism. Shoppers often buy excess food and leave fresh fruit and vegetables to go mouldy before they are eaten. Using plant derived-technology, the protective peels of fruit and vegetables can now be enhanced, allowing them to stay fresh for triple the amount of time of regularly grown produce. As the freshness of the products is protected for longer, the logistical costs of a strictly controlled refrigerated supply chain are reduced, and in the long-term, food waste is minimized.

As it exists at the moment, the food supply chain is environmentally damaging. From growing meat in a lab to extending the lifespan of fresh food, bioengineers are now finding ways to improve sustainability in food production.

3 Ways to Reuse Water Using Renewable Energy

Water is essential to life, making it one of the most valuable resources on the planet. We drink it, use it to grow food and stay clean. However, water is of increasingly short supply and the Earth’s population only continues to expand. Many of the countries with the largest populations are also ones that use the most water. For instance, in the United States, the average person uses 110 gallons of water each day. Meanwhile, three-fourths of those living in Africa don’t have access to clean water.

To ensure we have enough water to survive — and share with those in need — the best approach is to conserve this resource and find sustainable ways of recycling it. Currently, conventional methods or water purification use about three percent of the world’s energy supply. This isn’t sustainable long-term and can have adverse effects on the environment.

Recently, however, major steps have been made to reduce both the collective water and carbon footprint. Now, there are multiple, sustainable ways to both save energy and reuse water using renewable energy.

1. Anaerobic Digestion

Anaerobic digestion — or AD — is the natural process in which microorganisms break down organic materials like industrial residuals, animal manure and sewage sludge. This process takes place in spaces where there is no oxygen, making it an ideal system for cleaning and reusing wastewater. This recycled water can provide nutrients for forest plantations and farmland alike.

For example, in Yucatan, Mexico, the successful implementation of AD systems has provided water to promote reforestation efforts. This system has also helped accelerate the search for a sustainable solution to water-sanitation issues in rural Latin American communities.

Additionally, anaerobic digestion also reduces adverse environmental impacts. As the system filters water, it creates two byproducts — biogas and sludge. The biogas can be used as energy to supply electricity or even fuel vehicles. And the sludge is used as fertilizers and bedding for livestock. In poor countries, like Peru, 14 percent of primary energy comes from biogas, providing heat for food preparation and electricity to homes that would not have access to it otherwise.

2. Vapor Compression Distillation

In this process, the vapor produced by evaporating water is compressed, increasing pressure and temperature. This vapor is then condensed to water for injection — highly purified water that can be used to make pharmaceutical-grade solutions.

Vapor compression distillation is incredibly sustainable because it can produce pure water on combustible fuel sources like cow dung — no chemicals, filters or electricity necessary. This makes it water accessible to even the most rural communities.

The system only needs enough energy to start the first boil and a small amount to power the compressor. This energy can be easily supplied by a solar panel, producing roughly 30 liters of water an hour using no more energy than that of a handheld hairdryer.

3. Solar Distillation

Utilizing solar energy for water treatment may be one of the most sustainable solutions to the water crisis, without sacrificing the environment or non-renewable resources. Between 80 and 90 percent of all energy collected through commercial solar panels is wasted, shed into the atmosphere as heat. However, recent advancements in technology have allowed scientists to capture this heat and use it to generate clean, recycled water.

By integrating a solar PV panel-membrane distillation device behind solar panels, researchers were able to utilize heat to drive water distillation. This panel also increases solar to electricity efficiency. This device can even be used to desalinate seawater, providing a sustainable solution to generating freshwater from saltwater.

Environmental and Economic Benefits

Finding sustainable methods of recycling water is essential to reducing energy consumption and helping the planet, and all those dependent upon it, thrive. Using methods like anaerobic digestion and environmentally-friendly distillation processes can reduce toxic emissions and provide purified, recycled water to those who need it most.

Sustainable reuse of water can also benefit the economy. The financial costs of constructing and operating desalination and purification systems are often high compared to the above solutions. Furthermore, using recycled water that is of lower quality for agricultural and reforestation purposes saves money by reducing treatment requirements.

Comparison of MSW-to-Energy Processes

MSW-to-Energy is the use of thermochemical and biochemical technologies to recover energy, usually in the form of electricity, steam and other fuels, from urban wastes. The main categories of MSW-to-energy technologies are physical technologies, which process waste to make it more useful as fuel; thermal technologies, which can yield heat, fuel oil, or syngas from both organic and inorganic wastes; and biological technologies, in which bacterial fermentation is used to digest organic wastes to yield fuel. These new technologies can reduce the volume of the original waste by 90%, depending upon composition and use of outputs.

Components of MSW-to-Energy Systems

  1. Front-end MSW preprocessing
  2. Conversion unit (reactor or anaerobic digester)
  3. Gas cleanup and residue treatment plant
  4. Energy recovery plant (optional)
  5. Emissions clean up

Incineration

  • Combustion of raw MSW, moisture less than 50%
  • Sufficient amount of oxygen is required to fully oxidize the fuel
  • Combustion temperatures are in excess of 850oC
  • Waste is converted into CO2 and water concern about toxics (dioxin, furans)
  • Any non-combustible materials (inorganic such as metals, glass) remain as a solid, known as bottom ash (used as feedstock in cement and brick manufacturing)
  • Air pollution control system for fly ash, bottom ash, particulates etc.
  • Needs high calorific value waste to keep combustion process going, otherwise requires high energy for maintaining high temperatures

Anaerobic Digestion

  • Well-known biochemical technology for organic fraction of MSW and sewage sludge.
  • Biological conversion of biodegradable organic materials in the absence of oxygen at mesophilic or thermophilic temperatures.
  • Residue is stabilized organic matter that can be used as soil amendment
  • Digestion is used primarily to reduce quantity of sludge for disposal / reuse
  • Methane gas is generated which is used for heat and power generation.

Gasification

  • Can be seen as between pyrolysis and combustion (incineration) as it involves partial oxidation.
  • Exothermic process (some heat is required to initialize and sustain the gasification process).
  • Oxygen is added but at low amounts not sufficient for full oxidation and full combustion.
  • Temperatures are above 650oC
  • Main product is syngas, typically has net calorific value of 4 to 10 MJ/Nm3
  • Other product is solid residue of non-combustible materials (ash) which contains low level of carbon

Pyrolysis

  • Thermal degradation of organic materials through use of indirect, external source of heat
  • Temperatures between 300 to 850oC are maintained for several seconds in the absence of oxygen.
  • Product is char, oil and syngas composed primarily of O2, CO, CO2, CH4 and complex hydrocarbons.
  • Syngas can be utilized for energy production or proportions can be condensed to produce oils and waxes
  • Syngas typically has net calorific value (NCV) of 10 to 20 MJ/Nm

Plasma Gasification

  • Use of electricity passed through graphite or carbon electrodes, with steam and/or oxygen / air injection to produce electrically conducting gas (plasma)
  • Temperatures are above 3000oC
  • Organic materials are converted to syngas composed of H2, CO
  • Inorganic materials are converted to solid slag
  • Syngas can be utilized for energy production or proportions can be condensed to produce oils and waxes

MSW-to-energy technologies can address a host of environmental issues, such as land use and pollution from landfills, and increasing reliance on fossil fuels. In many countries, the availability of landfill capacity has been steadily decreasing due to regulatory, planning and environmental permitting constraints. As a result, new approaches to waste management are rapidly being written into public and institutional policies at local, regional and national levels.

Food Waste Management in UK

Food waste in the United Kingdom is a matter of serious environmental, economic and social concern that has been attracting widespread attention in recent years. According to ‘Feeding the 5K’ organisation, 13,000 slices of crusts are thrown away every day by a single sandwich factory. More recently, Tesco, one of the largest UK food retailers, has published its sustainability report admitting that the company generated 28,500 tonnes of food waste in the first six months of 2013. TESCO’s report also state that 47% of the bakery produced is wasted. In terms of GHG emissions, DEFRA estimated that food waste is associated with 20 Mt of CO2 equivalent/year, which is equivalent to 3% of the total annual GHG emissions.

Food-Waste-UK

Globally, 1.2 to 2 billion tonnes (30%-50%) of food produced is thrown away before it reaches a human stomach. Food waste, if conceived as a state, is responsible for 3.3 Bt-CO2 equivalent/year, which would make it the third biggest carbon emitter after China and USA.

What makes food waste an even more significant issue is the substantially high demand for food which is estimated to grow 70% by 2050 due to the dramatic increase of population which is expected to reach 9.5 billion by 2075. Therefore, there is an urgent need to address food waste as a globally challenging issue which should be considered and tackled by sustainable initiatives.

A War on Food Waste

The overarching consensus to tackle the food waste issue has led to the implementation of various policies. For instance, the European Landfill Directive (1999/31/EC) set targets to reduce organic waste disposed to landfill in 2020 to 35% of that disposed in 1995 (EC 1999).

More recently, the European Parliament discussed a proposal to “apply radical measures” to halve food waste by 2025 and to designate the 2014 year as “the European Year Against Food Waste”. In the light of IMechE’s report (2013), the United Nations Environment Programme (UNEP) in cooperation with FAO has launched the Save Food Initiative in an attempt to reduce food waste generated in the global scale.

In the UK, WRAP declared a war on food waste by expanding its organic waste programme in 2008 which was primarily designed to “establish the most cost-effective and environmentally sustainable ways of diverting household food waste from landfill that leads to the production of a saleable product”. DEFRA has also identified food waste as a “priority waste stream” in order to achieve better waste management performance.

In addition to governmental policies, various voluntary schemes have been introduced by local authorities such as Nottingham Declaration which aims to cut local CO2 emissions 60% by 2050.

Sustainable Food Waste Management

Engineering has introduced numerous technologies to deal with food waste. Many studies have been carried out to examine the environmental and socio-economic impacts of food waste management options. This article covers the two most preferable options; anaerobic digestion and composting.

In-vessel composting (IVC) is a well-established technology which is widely used to treat food waste aerobically and convert it into a valuable fertilizer. IVC is considered a sustainable option because it helps by reducing the amount of food waste landfilled. Hence, complying with the EU regulations, and producing a saleable product avoiding the use of natural resources.

IVC is considered an environmentally favourable technology compared with other conventional options (i.e. landfill and incineration). It contributes less than 0.06% to the national greenhouse gas inventories. However, considering its high energy-intensive collection activities, the overall environmental performance is “relatively poor”.

Anaerobic Digestion (AD) is a leading technology which has had a rapidly growing market over the last few years. AD is a biologically natural process in which micro-organisms anaerobically break down food waste and producing biogas which can be used for both Combined Heat & Power (CHP) and digestate that can be used as soil fertilizers or conditioners. AD has been considered as the “best option” for food waste treatment. Therefore, governmental and financial support has been given to expand AD in the UK.

AD is not only a food waste treatment technology, but also a renewable source of energy. For instance, It is expected that AD would help the UK to meet the target of supplying 15% of its energy from renewable sources by 2020. Furthermore, AD technology has the potential to boost the UK economy by providing 35,000 new jobs if the technology is adopted nationally to process food waste. This economic growth will significantly improve the quality of life among potential beneficiaries and thus all sustainability elements are considered.

Biomethane Utilization Pathways

Biogas can be used in raw (without removal of CO2) or in upgraded form. The main function of upgrading biogas is the removal of CO2 (to increase the energy content) and H2S (to reduce risk of corrosion). After upgrading, biogas becomes biomethane and possesses identical gas quality properties as  natural gas, and can thus be used as natural gas replacement. The main pathways for biomethane utilization are as follows:

  • Production of heat and/or steam
  • Electricity production / combined heat and power production (CHP)
  • Natural gas replacement (gas grid injection)
  • Compressed natural gas (CNG) & diesel replacement – (bio-CNG for transport fuel usage)
  • Liquid natural gas (LNG) replacement – (bio-LNG for transport fuel usage)

Prior to practically all utilization options, the biogas has to be dried (usually through application of a cooling/condensation step). Furthermore, elements such as hydrogen sulphide and other harmful trace elements must be removed (usually trough application of an activated carbon filter) to prevent adverse effects on downstream processing equipment (such as compressors, piping, boilers and CHP systems).

biomethane-transport

Although biogas is perfectly suitable to be utilized in boilers (as an environmental friendlier source for heat and steam production), this option is rather obsolete due to the abundance of alternative sources from solid waste origin.

Most Palm Oil Mills are already self-reliant with respect to heat and steam production due to the combustion of their solid waste streams (such as EFB and PKS). Consequently, conversion to electricity (by means of a CHP unit) or utilization as natural gas, CNG or LNG replacement, would be a more sensible solution.

The biogas masterplan as drafted by the Asia Pacific Biogas Alliance foresees a distribution in which 30% of the biomethane is used for power generation, 40% for grid injection and 30% as compressed/liquefied fuel for transportation purpose (Asian Pacific Biogas Alliance, 2015).

For each project, the most optimal option has to be evaluated on a case to case basis. Main decision-making factors will be local energy prices and requirements, available infrastructure (for gas and electricity), incentives and funding.

For the locations where local demand is exceeded, and no electricity or gas infrastructure is available within a reasonable distance (<5-10 km, due to investment cost and power loss), production of CNG could offer a good solution.

Moreover, during the utilization of biogas within a CHP unit only 40-50% of the energetic content of the gas is converted into electricity. The rest of the energy is transformed into heat. For those locations where an abundance of heat is available, such as Palm Oil Mills, this effectively means that 50-60% of the energetic content of the biogas is not utilized. Converting the biogas into biomethane (of gas grid or CNG quality) through upgrading, would facilitate the transportation and commercialisation of over 95%  of the energetic content of the biogas.

Within the CNG utilization route, the raw biogas will be upgraded to a methane content of >96%, compressed to 250 bar and stored in racks with gas bottles. The buffered gas (bottles) will be suitable for transportation by truck or ship. For transportation over large distances (>200km), it will be advised to further reduce the gas volume by converting the gas to LNG (trough liquefaction).

Overall the effects and benefits from anaerobic digestion of POME and utilization of biomethane can be summarized as follows:

  • Reduction of emissions i.e. GHG methane and CO2
  • Reduced land use for POME treatment
  • Enhanced self-sufficiency trough availability of on-site diesel replacement (CNG)
  • Expansion of economic activities/generation of additional revenues
    • Sales of surplus electricity (local or to the grid)
    • Sales of biomethane (injection into the natural gas grid)
    • Replacement of on-site diesel usage by CNG
    • Sales of bottled CNG
  • Reducing global and local environmental impact (through fuel replacement)
  • Reducing dependence on fossil fuel, and enhances fuel diversity and security of energy supply
  • Enhancement of local infrastructure and employment
    • Through electrical and gas supply
    • Through Fuel (CNG) supply

Co-Authors: H. Dekker and E.H.M. Dirkse (DMT Environmental Technology)

Note: This is the second article in the special series on ‘Sustainable Utilization of POME-based Biomethane’ by Langerak et al of DMT Environmental Technology (Holland). The first article can be viewed at this link